Disposable sabot



5 R O T m V m ATTORNEY AGE/VT DISPOSABLE SABOT R. HAMILTON ETAL Filed March 15, 1965 Oct. 4, 1966 RUSSELL HAMILTON FIG. 2

United States Patent 3,276,150 DISPOSABLE SABOT Russell Hamilton, Palo Alto, and Tsoy K. Moy, Santa Clara, Calif, assignors, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed Mar. 15, 1965, Ser. No. 440,035 5 Claims. (Cl. 35-25) The present invention relates to test equipment and more particularly to a disposable sabot which can be utilized to simulate the launching of a missile from a launching tube. 1

Those concerned with the development of tube launched missiles and, more particularly, the submarine launched missiles have long recognized the need for a test vehicle which can be used to simulate a missile launch to thereby permit checking out of the launching equipment and training of the launching crew without the necessity of utilizing either an actual or a dummy missile. For this purpose, water slug launches have proven the most realistic approach for checkout of launching system operation since they exercise much of the equipment and many of the circuits used in a normal missile launch. Essentially, a water slug is a column of water approximating the weight of the missile to be simulated, which water slug is disposed in the launcher tube and sealed off from the eject chamber by installation of a piston-like sabot therebeneath. Upon launch, the sabot and the water are forced out of the launcher tube, thereby simulating the launching of an actual missile.

In the past, the sabot consisted of a steel drum filled with a foam plastic and reinforcing steel. The buoyancy of the prior art sabot was such that it would float to the surf-ace of the water after launching so that it could be recovered and so that it would not fall back on, and damage, the submerged submarine from which it was launched. By remaining afloat, however, the sabot was a hazard to surface navigation and, due to its large weight and size, was very difficult if not impossible to recover by the launching submarine, particularly during rough sea conditions.

Therefore, the general purpose of this invention is to provide a disposable sabot which embraces all of the advantages of similarly employed sabots and which possesses none of the aforedescribed disadvantages. To obtain this, the present invention utilizes a unique construction and flotation device which enables the sabot to float at the surface of the water for a predetermined period of time before sinking to the ocean floor, thereby allowing the launching submarine time to move out from underneath it while also eliminating the hazard to surface navigation.

Accordingly, an object of the present invention is to provide a disposable sabot which is neither a hazard to the submarine from which it is launched nor to surface vessels.

Another object of the present invention is to provide a sabot which will float for a predetermined period of time prior to sinking.

A further object of the invention is to provide a sabot which provides launch and post launch performance characteristics which closely simulate the performance characteristics of an actual missile.

Still another object is the provision of a sabot which provides a solid interface between the water column and the gas which is used to launch same.

Yet another object of the present invention is to provide a sabot which has adequate guiding surfaces so that it will not scrape or score the launcher tube or tilt therein during a simulated launch.

3,276,150 Patented Oct. 4, 1966 A still further object of the invention is to provide a sabot constructed of non-metallic materials so that, when sunken, it will not affect mine detection or sonar equipment in the test area.

Yet another object of the present invention is to provide a sabot which is characterized by low cost, light weight, high strength and simplicity of construction.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings in which:

FIG. 1 is a sectional view of a missile launching submarine showing the sabot of the present invention in the launching tubes thereof; and

FIG. 2 is a perspective view, partly broken away, of the sabot of the present invention.

Referring now to the drawings wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in FIG. 1, in cross section, a missile launching submarine having an outer hull 10, a pair of missile launching tubes 12, an outer top hatch 14 for each of the tubes 12 and a pair of gas generator assemblies 16. A sabot 18 of the present invention is supported on a missile support ring 20 in each of the launching tubes 12, the rings 20 being disposed above pressure eject chambers 21 which are in communication with the gas generators 16. A water slug, the top of which is indicated by reference numeral 22, partially fills the launcher tube 12 above the sabot 18. The combined weight of the water slug and the sabot 18 is calculated to approximately equal the weight of the missile to be simulated.

When a test firing is commenced, the top hatch 14 of launching tube 12 is opened and the gas generator 16 is activated. The pressurized gas issuing from the gas generator 16 enters the pressure eject chamber 21 and forces the sabot 18 and the column of water thereabove out the muzzle end of the missile launching tube 12, thereby simulating an actual missile launch. It should be noted, of course, that a launch can be accomplished with either the submarine submerged or surfaced; however, when submerged, the launching tube is initially pressurized to a pressure substantially that of the surrounding sea water and the top of the launching tube is sealed with either a foam disk or a thin diaphragm to prevent the surrounding sea water from entering the tube.

As more clearly illustrated in FIG. 2, the sabot, generally indicated by reference character 18, is comprised of an inverted dish or dome-shaped member 23 having a radially extended seat ring or flange 24 extending around the entire periphery thereof. The seat ring 24 is bonded to the periphery of the dish 23 and is faced on the bottom surface thereof with a sealing strip 26 of Ensolite, or the like, that forms the contacting surface between the sabot 18 and the support ring 20 of the launching tube 12. The Ensolite sealing strip 26 is comprised of a soft flexible foam and, therefore, sealing of the sabot is achieved by compression thereof when water is pumped into the launching tube on top of the sabot.

Four upwardly projecting lobes of a generally arcuate truncated configuration are bonded to the upper convex surface of the dome 23 to add strength and rigidity to the sabot assembly and to provide vertical guiding surfaces therefor, thereby preventing the sabot 18 from damaging the launcher tube 12 and from tilting therein during launch. In addition, each upwardly projecting lobe 28 is provided with a t1e-bar 30 secured through a pair of apertures in the upper sidewalls thereof. A plurality of cross ties 32 of fiberglass tape or the like are wrapped around oppositely disposed tie-bars 30 to 3 prevent spreading of the lobes 28 when the sabot 18 emerges from the launching tube 12. As shown in the drawing, two parallel bands of glass tape are utilized to secure opposite pairs of the tie-bars 30 together; however, any conventional cross the mechanism could be utilized.

The inner concave surface of the dome 23 is provided with a flotation chamber 34 bonded thereto. The flotation chamber may be constructed in the form of a single continuous annulus, as shown in the drawing, or made up of a plurality of individual flotation chambers secured together. A plurality of apertures 36 is provided in the lower surface of the flotation chamber 34, the purpose of which is hereinafter set forth.

The individual components of the sabot 18 may be formed separately of laminated fiberglass using con-"ventional fiberglass layup techniques and then bonded together into an integral unit or the components may be made of other high strength plastic materials molded as a unitary assembly.

In operation, the assembled sabot 18 with the lobes 28 pointing upwardly is lowered into the launch tube 12, by means of a sling or hook secured around each of the tie bars '34), until the sabot seat ring 24 with the sealing ring 26 thereon rests on the missile support ring 20 of the launcher tube 12. The tube above the sabot 18 is then filled with water to the proper level for the desired weight. As is apparent, the sabot dish 23 supports the weight of the water above it during the period prior to launching while the sealing strip 26 prevents leakage into the pressure eject chamber 21. The apertures 36 in the flotation chamber 34 maintain this chamher at the ambient pressure within the eject chamber 21.

When the gas generators 16 are activated and the pressure eject chamber 21 is pressurized, the sabot 18 is forced off of the support ring 20 and caused to move up the launching tube 12, forcing the water above it out the muzzle end thereof after rupturing the tube seal. As the sabot emerges from the tube, the glass tape cross ties 32 resists the hydrodynamic load imposed thereon by the surrounding sea water and restrains the lobes from spreading and separating from the dish 23. The flotation chamber 34, being filled with air or gas through apertures 36 from the pressure eject chamber 21, permits the sabot to have temporary buoyance thereby causing it to float to the surface of the water. This eliminates any possibility of fallback damage to the launching submarine by providing a delay, thereby permitting the submarine to move out from under the impact area. The sabot 18 will continue to float for a predetermined period of time until the flotation chamber 34 fills with sea water through apertures 36 whereupon it Will sink to the ocean floor, thereby also eliminating it as a navigational hazard to surface vessels. Since the sabot is constructed of non-metallic materials, it will not affect mine detection or sonar equipment in the test area. Of course, if desired, the sabot may be recovered during the period in which it remains afloat.

There has, therefore, been described a disposable sabot which is constructed of a light weight and inexpensive material, which can be utilized to simulate the launch of an actual missile, which will not damage the launch- 4 ing equipment and which is neither a hazard to the launching submarine nor to surface vessels.

It is to be understood, of course, that the foregoing disclosure relates to only a preferred embodiment of the invention and that many modifications or alterations may be made therein without departing from the spirit and scope of the invention as set fort-h in the appended claims.

What is claimed is: 1. A disposable sabot comprising: an inverted concavo-convex dome having a radially extending seat ring disposed around the periphery thereof; a sealing strip bonded to the lower face of said peripheral seat ring; a plurality of upwardly projecting arcuate guide members secured to the upper convex surface of said dome, each of said guide members having a tie bar secured thereto near its uppermost end; a plurality of cross ties secured to said tie bars for preventing outward spreading of said guide members; and a flotation chamber secured to the inside concave surface of said dome, said flotation chamber having a plurality of apertures in the walls thereof to permit said chamber to fill with water and sink after a predetermined period of time. 2. A disposable sabot for simulating a missile launch comprising:

a dome-shaped base member having a peripheral radially extending flange; seal means disposed on said flange; guide means secured to the upper convex surface of said base member; and

means for providing temporary buoyancy of said sabot in water;

whereby, after launching, the sabot will float for a predetermined period of time and then will sink.

3. A disposable sabot, as set forth in claim 2, wherein:

said guide means comprises a plurality of upwardly projecting arcuate members reinforced with a plurality of cross ties; and

said means for providing temporary buoyancy comprises a flotation chamber secured to the inside concave surface of said base member, said chamber having a plurality of apertures in the walls thereof.

4. A disposable sabot, as set forth in claim 3, wherein the entire sabot is constructed of non-metallic materials.

5. A sabot for simulating a missile launch in a launching tube comprising:

a base member having a diameter slightly less than the diameter of the launching tube;

guide means secured .to said base member for guiding the sabot through the launching tube; and

flotation means having a plurality of apertures in the walls thereof for providing temporary buoyancy of the sabot in water.

No references cited.

EUGENE R. CAPOZIO Primary Examiner. R. E. KLEIN, Assistant Examiner. 

5. A SABOT FOR SIMULATING A MISSILE LAUNCH IN A LAUNCHING TUBE COMPRISING: A BASE MEMBER HAVING A DIAMETER RIGIDLY LESS THAN THE DIAMETER OF THE LAUNCHING TUBE; GUIDE MEANS SECURED TO SAID BASE MEMBER FOR GUIDING THE SABOT THROUGH THE LAUNCHING TUBE; AND FLOTATION MEANS HAVING A PLURALITY OF APERTURES IN THE WALLS THEREOF FOR PROVIDING TEMPORARY BUOYANCY OF THE SABOT IN WATER. 